The researchers measured a parameter called the 'seeing' at the site, on a 3260 metre high plateau in central Antarctica. The site is at the French-Italian Concordia research station 1100 kilometres inland from Australia's Casey station and the French station at Dumont D'Urville.

Because of the height, dryness and stillness at Dome C, the Earth's atmosphere doesn't affect the light from stars in the same way it does at other sites.

Seeing is believingThe results showed that Dome C was two and a half times better than any alternative site and at its best almost as good as the Hubble Space Telescope, the researchers said.

"A two metre telescope at Dome C would compete with a six to eight metre telescope anywhere else in the world at 20 to 30 times less cost," said co-author Associate Professor Michael Ashley.

Seeing is a measurement of the turbulence in the atmosphere from wind and temperature differences, and how these affect ground-based observations. It is measured using arc seconds, one arc second being 1/3600th of a degree, and a lower score is better.

On average the seeing at Dome C is 0.27 arc seconds and has been as low as 0.07 arc seconds. The best mid-latitude sites are 0.5 to 1.0 arc seconds.

"The seeing is something that until now has been quite unknown. People had postulated that it might be very good but until now no-one had proved it," said Ashley.

The clarity and resolution at Dome C would allow astronomers to take photos of planets orbiting other stars, Ashley said.

Currently these extrasolar planets can only be seen indirectly, by measuring the wobble caused by large planets orbiting close to their parent star, or the tiny drop in brightness of a star as a planet passes in front of it.

"You could certainly detect Jupiter-sized planets and the aim is to detect Earth-sized planets," Ashley said.

The phone used to call the telescope (Image: UNSW)

Calling to a lonely placeThe researchers used a robotic telescope to make the measurement during the Antarctic winter. They sent information to and from the telescope by satellite phone and could send commands via mobile phone.

The telescope was housed inside the 'green tomato', the University of New South Wales' Automated Astrophysical Site Testing International Observatory.

The station has so far only operated in the summer though scientists will spend winter there next year.

An optical telescope based at Dome C could only operate during winter while the Sun is below the horizon. But an infrared telescope could operate all year round.

The new measurement puts the team in a stronger position to look for funding for a two-metre telescope to be build at the site, said Ashley.

"We don't want to become a 5% partner in the telescope, we want to run the show ourselves."

The researchers are applying for funding for a Centre of Excellence from the Australian government and already have international collaborators.

Eventually they hope to build an eight-metre telescope at the site, which would be the most powerful telescope in the world.